Support for rotor blades in a rotor

ABSTRACT

The blades are held in slots of the rotor along with baffle elements which are placed between each pair of blades. Each element is elastically connected in a yieldable manner to each blade of a pair of blades at points on opposite sides of the element while simultaneously filling the slot to prevent leakage between the blades. The elements can be slotted or provided with elevations at opposite ends to enhance the yieldability.

United States Patent Inventor Peter Suter n Schottikon, Zurich,Switzerland Appl. No. 813,235 Filed Apr. 3, 1969 Patented Oct. 5, 1971Assignee Sulzer Brothers, Ltd.

Winterthur, Switzerland Priority Aug. 9, 1968 Switzerland 1201 1/68SUPPORT FOR ROTOR BLADES IN A ROTOR 9 Claims, 7 Drawing Figs.

Int. Cl. F01d 5/32 Field of Search 253/77 CK, 77 PM; 416/221, 219, 220,210, 212,500

References Cited UNITED STATES PATENTS 12/1963 Morris 3,266,771 8/1966Morley 416/219 X 3,294,364 12/1966 Stanley 416/219 2,669,383 2/1954Purvis et al.. 416/221 UX 2,942,842 6/ l 960 Hayes 416/221 3,001,7609/1961 Guernsey et al. 416/221 3,008,689 11/1961 Morley et al 416/2213,037,741 6/1962 Tuft 416/221 3,119,595 l/l964 Wilson et a1. 416/220Primary Examiner-Everette A. Powell, Jr. Attorney Kenyon & Kenyon ReillyCarr & Chapin ABSTRACT: The blades are held in slots of the rotor alongwith baffle elements which are placed between each pair of blades. Eachelement is elastically connected in a yieldable manner to each blade ofa pair of blades at points on opposite sides of the element whilesimultaneously filling the slot to prevent leakage between the blades.The elements can be slotted or provided with elevations at opposite endsto enhance the yieldability.

PATENTED um 5 I971 Inventor PETE-F? SUTER SUPPORT FOR ROTOR BLADES IN AROTOR This invention relates to a support for rotor blades in a rotor.More particularly, this invention relates to a support for rotor bladesof a turboengine rotor.

Turboengine rotors have been known wherein a plurality of turbine bladeshave been mounted in slots within the rotor with wedgelike baffleelements therebetween. For example, blades have been constructed with abaseplate, a necklike extension below the baseplate and a base below theextension which has been shaped to mate within an axial or oblique slotin the rotor. In order to prevent leakage between these blades, thebaffle elements have been sized to fit within the space between thenecklike extension of two adjacent blades. Further, such baffle elementshave been sized and fitted so as to obtain as smooth as possible atransition between the baseplates and rotor.

However, it has been found that under the influence of centrifugalforce, the heretofore used baffle elements have been pressed with suchforce against the baseplates as to behave in a manner as if they wererigidly interconnected with the baseplates. Such rigid connections havefrequently exerted unfavorable influence on the vibration behavior ofthe rotor in that the natural vibration frequency of a row of blades hasbecome excessively high.

Accordingly, it is an object of the invention to mount the blades of arotor in place in an elastic manner.

It is another object of the invention to permit vibration of a turbineblade with respect to a baffle element adjacent the blade within arotor.

It is another object of the invention to reduce the natural vibrationfrequency of a blade secured in a rotor.

Briefly, the invention provides a baffle element for turbine blades in arotor which is situated between a pair of blades and contacts each bladeat a point in an elastic yieldable manner opposite the contact point ofthe other blade. This allows the blades to vibrate more or less freelywith respect to the baffle element. In effect, an elastic yieldablesection is provided in the baffle element between the contact pointswith the respective turbine blades. As a result, the blades are able tooscillate more or less freely with respect to the baffle element whiletheir natural frequency is reduced. Depending on the configuration ofthe intermediate baffle elements, the natural vibration frequency of theblades can be adjusted to a desired value within certain limits. Also,depending on the vibration form of particular interest, variousconfigurations of the baffle elements can likewise be elasticallyeffective.

These and other objects and advantages of the invention will become moreapparent from the following detailed description taken in conjunctionwith the accompanying drawings in which:

FIG. 1 illustrates a fragmentary side view of a rotor having bladesmounted in place by baffle elements according to the invention;

FIG. 2 illustrates a view taken on line A-B of FIG. 1;

FIG. 3 illustrates a perspective view of the baffle element of FIG. 1;

FIGS. 4 to 6 respectively illustrate perspective views of modifiedbaffle elements according to the invention; and

FIG. 7 illustrates a view similar to FIG. 1 of another modified baffleelement according to the invention.

Referring to FIG. 1, the rotor I is provided with a plurality ofcircumferentially spaced axial or oblique slots 2 each of which receivesa complementary shaped base 3 of a turbine blade 4. In addition to theshaped base 3, each blade 4 has a baseplate 5 and a necklike extension 6between the base 3 and baseplate 5. The necklike extensions 6 of eachpair of adjacent blades 4 are spaced apart to provide an interspace fora baffle element 7. Each baffle element 7 serves to fill up theinterspace between the blade extensions 6.

Referring to FIG. 3, each baffle element 7 has a pair of plates 8, whichare joined together in spaced relation by a crosspiece 9 ofsubstantially T-shaped cross section. In addition, elevations 11, I6 areprovided at either end of the crosspiece 9 to extend over a part of thelength of the crosspiece 9, for example, one-quarter of the crosspiecelength. The elevations ll, 16 are further disposed diagonally oppositeeach other on the top of the crosspiece 9. Thus, one elevation 11 comesin contact with the baseplate 3 of one turbine blade 4 while the otherelevation 16 comes in contact with the baseplate 3 of the other turbineblade 4 of an adjacent pair of blades. Also, one of the plates 8, i.e.,the front plate, of each baffle element 7 has a lug 18 extendingtherefrom in the same plane which abuts the side of a blade 4 so as toprevent axial displacement of the baffle element 7. Since each of thebaffle elements 7 contacts the baseplates 5 of adjacent blades 4 atseparated points and is of a shape to elastically yield under stress,the baseplates 5 can move with respect to one another, for example,under a torsional vibration.

Referring to FIG. 4 in order to increase the elastic yieldability, thebaffle element 7 is provided with a slot 14 substantially in the centerof the crosspiece 9 which passes upwardly through the upper part of thecross section of the crosspiece 9. Alternatively, a plurality of slots(not shown) can be distributed uniformly or nonuniformly over the lengthof the crosspiece 9.

Referring to FIG. 5, the elastic yieldability of the baffle element 7can also be increased by reducing the cross-sectional area of the centerof the crosspiece 9 in the upper part. For example, as shown, the flathorizontal upper part of the crosspiece can be centrally interrupted.

Referring to FIG. 6, the elastic yieldability of the baffle element canbe increased by positioning the two elevations 12 on the same side ofthe crosspiece 9. This allows the baffle element 7 to bear against onlyone of the two adjacent blades 4 during operation while the contactpoint of the baffle element 7 with the other blade 4 lies between theplates 8 and the necklike extension 6 substantially in the area 13, asshown, opposite the lug I8.

Referring to FIG. 7, a baffle element 7' having an axial slot 20 canalso be fitted between the necklike extensions 6 of a pair of blades 4.This allows an elastic yieldable connection to be formed at the contactpoints I9 between the upper surfaces of the element 7' on opposite sidesof the slot 20 and the baseplates 5 of the blades 4.

What is claimed is:

l. The combination of a rotor having a plurality of circumferentiallyspaced slots; a plurality of turbine blades mounted in respective slotsof said rotor, each blade having a base received in a respective slot, abaseplate and a necklike extension between said base and baseplate; anda plurality of elements, each said element being of approximately thesame axial length as said necklike extensions and positioned between apair of adjacent blades between said necklike extensions, each saidelement having a pair of spaced-apart elevations projecting therefrom,one of said elevations contacting one blade at a first contact point andthe other of said elevations contacting the other blade of said pair ofblades at a second contact point, and each said element beingelastically yieldable between said points of contact and saidelevations.

2. The combination as set forth in claim 1, wherein said elementincludes a pair of spaced plates between said pair of blades and acrosspiece joining said plates.

3. The combination as set forth in claim 2, wherein each baseplate isdisposed radially over said elements and wherein said crosspiece mountssaid elevations on an upper surface thereof with each said elevationextending along not more than one-quarter of the length of saidcrosspiece.

4. The combination as set forth in claim 3, wherein said crosspieceincludes at least one slot therein between said contact points.

5. The combination as set forth in claim 3, wherein said crosspiece hasa reduced cross section centrally thereof.

6. The combination as set forth in claim 2, wherein one of said platesof each element has a lug projecting therefrom in contact with the sideof an adjacent blade.

7. The combination as set forth in claim I, wherein said elementincludes an axial slot in the upper part between said contact points.

S. The combination as set forth in claim I, wherein said slots areobliquely disposed in said rotor.

9. The combination as set forth in claim 1 wherein said slots areaxially disposed in said rotor.

1. The combination of a rotor having a plurality of circumferentiallyspaced slots; a plurality of turbine blades mounted in respective slotsof said rotor, each blade having a base received in a respective slot, abaseplate and a necklike extension between said base and baseplate; anda pluraliTy of elements, each said element being of approximately thesame axial length as said necklike extensions and positioned between apair of adjacent blades between said necklike extensions, each saidelement having a pair of spaced-apart elevations projecting therefrom,one of said elevations contacting one blade at a first contact point andthe other of said elevations contacting the other blade of said pair ofblades at a second contact point, and each said element beingelastically yieldable between said points of contact and saidelevations.
 2. The combination as set forth in claim 1, wherein saidelement includes a pair of spaced plates between said pair of blades anda crosspiece joining said plates.
 3. The combination as set forth inclaim 2, wherein each baseplate is disposed radially over said elementsand wherein said crosspiece mounts said elevations on an upper surfacethereof with each said elevation extending along not more thanone-quarter of the length of said crosspiece.
 4. The combination as setforth in claim 3, wherein said crosspiece includes at least one slottherein between said contact points.
 5. The combination as set forth inclaim 3, wherein said crosspiece has a reduced cross section centrallythereof.
 6. The combination as set forth in claim 2, wherein one of saidplates of each element has a lug projecting therefrom in contact withthe side of an adjacent blade.
 7. The combination as set forth in claim1, wherein said element includes an axial slot in the upper part betweensaid contact points.
 8. The combination as set forth in claim 1, whereinsaid slots are obliquely disposed in said rotor.
 9. The combination asset forth in claim 1 wherein said slots are axially disposed in saidrotor.